Closure for a Container

ABSTRACT

A closure for a container comprises a circular base, a skirt extending from the periphery of the base, an outer seal, a plug seal in the form of an annulus, and at least one rib lying on the surface of the base in a substantially radial direction and in contact with the radially inner surface of the plug seal at one end for transferring any movement of the base, relative to the skirt, to the plug seal such that the plug seal is pulled radially inward to allow venting of excess pressure within the container. The outer seal of the closure comprises at least one deformation portion which partially interrupts the sealing effect of the outer seal in case overpressure occurs.

The present invention relates to a closure according to the preamble of the independent claim.

Screw closures for containers with pressurized fluids such as carbonated beverages are widely known. If the pressure build-up in the container exceeds a desired level sufficient to overcome the thread engagement, the closure may be suddenly ejected from the container neck, an effect also called “closure missiling” which may lead to possible injury of users.

Closures for container have therefore been developed, whereby excessive gas pressure in the container is decreased by automatic self-venting of the closure-container arrangement in the sense of a pressure control valve.

EP 0 858 416 discloses a closure with a base and a downwardly depending skirt defining the outside of the closure. Within the closure, a bore seal downwardly depends from the base. Radially between this bore seal and the skirt, a stop also downwardly depends from the base. This stop acts to prevent over-tightening of corresponding screw threads located within the shell and on an associated container, and acts against the rim of the container. Between the stop and the bore seal the thickness of the base is thinned. A rib of uniform thickness lying on the inside of the base extends from the bore seal towards the axial centre of the base and the bore seal is bulged radially outwardly by its presence in case of overpressure, whereby the container is vented.

The venting mechanism of EP 0 858 416 functions in that the thinned portion as described works as a hinge allowing the portion of the base, including the part which has the bore seal depending from it, to move upwards. Hence, the bore seal has to be lifted slightly from the inner side of the container neck to allow venting.

WO 2006/051068 discloses a closure suitable for self-venting of excessive gas by a rib which is lying on the surface of its base and in direct contact with a bore seal and transfers any movement of the centre of the base by excessive gas to that bore seal allowing venting.

In accordance with self-venting mechanism of WO 2006/051068 the bore seal moves away from the inner side of the container because of its direct contact to the neck.

The bore seal disclosed in these documents seals by pressing against the inner side of the neck of the container when the closure is applied. In this context, it is a known problem that damages or tortures at the rim or within the neck reduce the sealing effect.

Therefore, in case of damages or tortures at the inner surface of the container neck, such arrangements for self-venting further reduce the desired sealing effect of the bore seal or lead to premature venting intensifying the problem as mentioned.

It is therefore the object of the present invention to overcome the drawback of the prior art and in particular to provide a closure which supports the functionality of such bore seal to improve the sealing properties and thereby not decreasing the workability of the self-venting function.

This problem is solved with a closure according to the characterizing part of claim 1.

The invention provides a closure for a container comprising a circular base, a skirt extending from the periphery thereof, a plug seal in the form of an annulus, typically also called dive seal, and at least one rib lying on the surface of the base in a substantially radial direction.

The plug seal seals the closure against the inner side of the container. The rib is in contact with the radially inner surface of the plug seal at one end for transferring any movement of the base, relative to the skirt, to the plug seal such that the plug seal is pulled radially inward to allow venting of excess pressure within the container.

An outer seal is arranged concentrically to the skirt. Such outer seal seals against an outer surface of the container weal and further centers the closure against the container and generates a counterforce to the plug seal supporting its sealing properties against the container neck.

The outer seal has at least one deformation portion which is weaker than a main fraction of the outer seal and which will interrupt partially the sealing effect of the outer seal in case overpressure occurs. Such a deformation portion maintains the desired functionality of automatical self-venting, whereas, especially at normal gas and ambient temperature conditions in the container, the sealing effect at the position of such deformation portion is as effective as at the main fraction of the outer seal. The deformation portion may be formed by locally reducing the size of the seal, e.g. its axial length and/or by its radial thickness. The deformation portion might also be formed by influencing the material properties. The deformation portion may even break when extreme pressure conditions are built up inside the container.

The closure preferably comprises 6 main fraction and deformation portions, respectively, if the circular base has a diameter of 28 mm. The closure preferably comprises 8 or 9 main fractions and deformation portions, respectively, if the circular base has a diameter of 38 mm.

The closure provides further preferably a top bulge located at the under side of the upper wall between the plug seal and the outer seal. The top bulge features at least one gap whereby excessive gas can pass through. Thereby, in addition to the deformation portions, a defined route for the gas to escape strengthens the effect of self-venting.

Preferably, the top bulge is arranged concentrically to and between the plug seal and the outer seal

There is some free radial space between the top bulge and the outer seal such that excessive gas can reach and pass the deformation portion. However, preferably the gap of the top bulge is circumferentially aligned with the deformation portion to guarantee a defined and direct route for excessive gas, thereby increasing the effect of the self-venting.

The outer seal of the closure is preferably arranged vertically to the circular base or may be inclined slightly radially inwardly or outwardly. Such inclination of the outer seal will reduce the surface contact and thereby reduce friction, in order to keep removal torques low.

The end of the rib in contact with the radially inner surface of the plug seal is preferably thinner, in a plane parallel to the base, than in a region spaced from the end of the rib in contact with the radially inner surface, in particular thinner than the other end of the rib. A relatively thin contact to the plug seal brings several advantages such as a minimized reduction of the flexibility of the plug seal. Such an arrangement is described in WO 2006/051068.

The deformation portion may be formed by reduction of the radial thickness of the outer seal.

Preferably, the rib is aligned to a deformation portion in order to shorten the way of excessive gas when venting.

The deformation portions are preferably located in a constant circumferential distance to each other.

The radial angle included between the deformation portions is preferably between neighbourly internal sides of 34° to 50°, more preferably between 34° to 45°, most preferably 34° to 40°. A constant distance between the deformation portion leads to a homogeneous force allocation and centering when the closure is applied to the container. Furthermore, self-venting is effected homogeneously over the whole circumference of the outer seal.

Furthermore, the thickness of those deformations portions is preferably between 0.3 to 0.5 mm, more preferably between 0.3 to 0.4 mm, as compared to a thickness of 0.7 mm of the outer seal.

The circumferential length of the deformation portion is determined by a radial angle from the centre of the circular base including preferably between 6° to 30°, more preferably between 6° to 20°, most preferably between 6° to 15°.

Embodiments of the inventions will now be described, by way of example, with reference to the following drawings.

FIG. 1 shows an external view on the closure shell

FIG. 2 shows a cross-sectional view of the closure when self-venting

FIG. 3 shows a plan view of a part of the base of the closure

FIG. 1 shows an external view on a closure 10. A base 20 is comprised as a circular upper fundament and depending downwardly from its periphery is a skirt 30.

FIG. 2 shows approximately half of the closure shell 10 in cross-section. The base 20 may be seen here and depending downwardly from its periphery is the skirt 30.

Located at the inner surface of this skirt 30 are screw threads 40. These screw threads 40 cooperate with corresponding container screw threads 45 located on a radially outer surface of a container.

Moreover, an olive type plug seal 50 is depending downwardly from the base 20 extending in a complete annulus as shown in FIG. 3 and which seals with a radially projecting rib 51 against an inner side of a neck of a container.

A top bulge 70 acts as a limitation for the container progressing towards the base 20. The top bulge 70 is interrupted with at least one gap 75 constituting a passage for excessive gas P and the gap of the top bulge 70 is aligned with the deformation portion as also shown in FIG. 3.

Concentrically to and as a next inner annulus to the skirt 30 is an outer seal 60 depending vertically from the base 20. The outer seal 60 may also be slightly inclined radially inwardly or outwardly. The outer seal 60 is provided with at least one deformation portion 65 which is relatively thinner than a main fraction 61 of the outer seal 60.

A rib 80 extends radially between a position of the base 20 and the inner surface of the plug seal 50.

FIG. 3 shows a plan view of a part of the base of the closure. FIG. 3 shows a base 20 which is substantially circular. Depending downwardly from the base 20 and extending as a complete annulus from the centre of the base 20 is the plug seal 50, thereby providing a seal with an inside of a neck of a container as can be seen in FIG. 1.

The outer seal 60 is arranged concentrically to the skirt 30. At least one deformation portion 65 is shown as part of the outer seal 60 which is relatively thinner than the main fraction 61 of the outer seal 60.

In a preferred embodiment, the thickness of those deformation portions 65 is between 0.3 to 0.4 mm.

The radial angle between lateral sides of the deformation portions 65 is between 34° to 40° and includes a constant circumferential length between the deformation portions 65.

The circumferential length of the deformation portion 65 is determined by a radial angle of the circular base 20 including 6° to 15°.

Such closures comprise 8 or 9 deformation portions 65 and main fractions 61, respectively and their circular base 20 has a diameter of 38 mm.

The closure with 8 deformation portions 65 and main fractions 61, respectively, comprises a thread 40 which is two-start. The closure with 9 deformation portions 65 and main fractions 61, respectively, comprises a thread 40 which is three-start.

The top bulge 70 is located radially outwardly to the plug seal 50. The top bulge 70 is placed between the plug seal 50 and the outer seal 60. The top bulge 70 is thereby interrupted by at least one gap 75 defining a passage for excessive gas P during self-venting.

The rib 80 extends radially between a position of the base 20 and the inner surface of the plug seal 50. It may been seen in FIG. 2 that the end 81 of the rib 80 contacting the inner surface of the plug seal 50 is thinner compared with the opposite end 84. It may be seen that the rib 80 has a first part 83 and a second part, the second part terminating at an end 81 in contact with the plug seal 50 and the first part 83 extending radially inwards from the other end of the second part. In a preferred embodiment, the first part 81 of the rib 80 is substantially stiffer than the second part 82. 

1-12. (canceled)
 13. A closure for a container comprising a circular base, a skirt extending from the periphery thereof, a plug seal in the form of an annulus and at least one rib lying on the surface of the base in a substantially radial direction and in contact with a radially inner surface of the plug seal at one end for transferring any movement of the base, relative to the skirt, to the plug seal such that the plug seal is pulled radially inward to allow venting of excess pressure within the container, wherein the closure is provided with an outer seal having at least one deformation portion to deform in the case of overpressure to partially interrupt a sealing effect of the outer seal.
 14. The closure according to claim 13, wherein a top bulge is located at an underside of the base concentrically to and between the plug seal and the outer seal and interrupted with at least one gap.
 15. The closure according to claim 14, wherein the gap of the top bulge is aligned with the deformation portion.
 16. The closure according to claim 13, wherein the outer seal is inclined radially inwardly.
 17. The closure according to claim 13, wherein the outer seal is inclined radially outwardly.
 18. The closure according to claim 13, wherein an end of the rib in contact with the radially inner surface of the plug seal is thinner, in a plane parallel to the base, than in an area of the rib arranged spaced from the inner surface of the plug seal.
 19. The closure according to claim 13, wherein the rib has a first part and a second part, the second part terminating at an end in contact with the plug seal and the first part extending radially inwards from the other end of the second part.
 20. The closure according to claim 19, wherein the first part of the rib is substantially stiffer than the second part.
 21. The closure according to claim 13, wherein the rib is aligned to a deformation portion.
 22. The closure according to claim 13, wherein the deformation portions are distanced constantly and an angle included between lateral sides of the deformations portions is preferably between 34° to 50°.
 23. The closure according to claim 13, wherein a thickness of the deformation portions is preferably between 0.3 to 0.5 mm as compared to a thickness of 0.7 mm of the outer seal.
 24. The closure according to claim 13, wherein a circumferential length of the deformation portion is determined by a radial angle from the centre of the circular base including preferably between 6° to 30°.
 25. The closure according to claim 22, wherein the angle is between 34° to 45°.
 26. The closure according to claim 22, wherein the angle is between 34° to 40 °.
 27. The closure according to claim 23, wherein the thickness is between 0.3 to 0.4 mm.
 28. The closure according to claim 23, wherein the radial angle is between 6° to 20°.
 29. The closure according to claim 23, wherein the radial angle is between 6° to 15°. 